Machining unit with a rotating head

ABSTRACT

The machining unit is composed mainly of three essential elements which are the rotor, the phase displacement device and the tool drive mechanism. The rotor (100) includes a rotating shaft (1) and is equipped, for example, with four bores, extending parallel to the axis of rotation, into which the cutter carrier axles (9a, 9b, 9c and 9d) are supported. A plunge of the cutters into the material to be machined is controlled by the movement of a command sleeve (19) supporting, at its end, two surfaces (20a and 20b) of ellipsoidal form located to move, in conjunction with the inclined surfaces (14a, 14b, 14c and 14d), the command levers of the tool carrier. The command sleeve can occupy two extreme positions and one intermediary position. A phase displacement device includes a pulley (22) and a reverse pulley (25) mounted rotatably on a shaft (31) to allow angular phase change of the command sleeve (19) with respect to the spindle.

FIELD OF THE INVENTION

The present invention concerns a machining unit with a rotating headsupporting at least two pairs of pivoting tools for the manufacturing ofa non-rotating piece centered along the axis of the rotating head,comprising:

a framework upon which is mounted a rotor comprising the rotating headand a spindle integral with this head, the rotor being provided with anaxial conduit for a guiding cylinder of a wire to be machined, andcoupled with means for providing rotational drive,

means for axial control of the piece, these means being mounted bybearings to the spindle or the rotating head,

means for maintaining and axially moving the piece,

at least four tool supports mounted on the rotating head in such a wayas to pivot around respective axles extending parallel to the rotationaxis, each support comprising a transversely arranged command lever, and

means for controlling pivoting in conjunction with said command leverand including a rotating command element, that is axially movable in therotor, and coupled to means for axially moving a command sleeve, andpairs of support members respectively arranged on each command lever andon the corresponding rotating element, each pair of support membersincluding a directing surface and a support surface supporting itselfagainst the directing surface, in a variable position, in relation tothe movement of the rotating command element, said directing surfacebeing located on the tool support and the corresponding drive surfacebeing located on the rotating command element, and each directingsurface corresponding to a pivoting tool support having the shape of anhelical portion whose axis coincides with the pivoting axis of the saidsupport.

DESCRIPTION OF THE RELATED ART

The machining head of this type, described in the internationalpublication WO 91/14527, includes a spindle tool carrier equipped withfour tools linked in pairs, each pair being controlled by a numberedaxis.

This configuration imposes the use of a relatively advanced controlmechanism whose price is high.

This constitutes a major inconvenience and prevents the production of amachine having a relatively low cost of manufacture. In order toalleviate this inconvenience, the present invention proposes to producea spindle having four coupled tools, but where only one pair of toolscan be operate at a time. The selection of the pair of tools, with whichmachining must be performed, must be able to be selected during rotationof the spindle which carries these tools.

BRIEF SUMMARY OF THE INVENTION

This aim is achieved by the machine unit according to the inventionwherein the command sleeve is mounted coaxially on said spindle, inorder to slide axially and to occupy a primary position, a secondaryposition and a middle position, this sleeve having two ellipsoidal drivesurfaces at one of its extremities, designed to cooperate with thehelical directing surfaces of the drive members and to execute theplunge of the tools, and a phase displacement device designed to causesaid command sleeve to rotate a predetermined angle around its axis.

According to a preferred embodiment, the means for axially moving thecommand sleeve includes a command lever pivoting about an axis mountedon a support fixed to the framework carrying the spindle, this levercomprising two drive nuts centered about axles and engaging respectivelytwo grooves located on opposite sides of a sleeve mounted coaxially onthe command sleeve.

The sleeve is preferably mounted on the command sleeve by means of twoball bearings with oblique preloaded contacts.

According to a particularly advantageous embodiment, the phasedisplacement device includes a pulley linked to the command sleeve bytwo cotter pins that assure a rotational coupling between said pulleyand said sleeve and that allow the latter free to move axially, saidpulley being coupled to a rotatable pulley mounted on a tubular supportsupporting a reverse pulley, mounted freely and linked to a drive pulleymounted on the spindle and driven by a drive motor.

The coupling between the pulley, linked to the command sleeve, and therotatable pulley can be executed by means of a belt.

The coupling between the reverse pulley and the drive pulley can beexecuted by means of a belt.

The phase displacement device preferably includes means to change theangular position of the rotatable pulley relative to the reverse pulley.

The means to advantageously change the angular position of the twopulleys includes two contacts integral with the reverse pulley engagedin two helical grooves of a shaft and two contacts integral with therotatable pulley engaged in two longitudinal grooves of said shaft, aswell as a member designed to move said shaft axially.

Said member is preferably a piston and said piston is preferably linkedto the shaft by means of a bell cover and a thrust bearing mounted atone end of this shaft.

Said piston is preferably linked to position sensors designed to providea receipt signal of its movement.

According to a preferred embodiment, the rotatable pulley and thereverse pulley are notched pulleys and have the same number of teeth.

In this case, the helical grooves are designed in such a way that whenthe piston moves the shaft from a first position towards a secondposition, the angular displacement of the pulley integral of the commandsleeve, with respect to the shaft integral with the spindle, is 90° atthe time when the number of pairs of tools carried by the machining headis equal to two.

The piston is preferably joined to an adjusting screw that limits itspath.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention will be better understood by referring to one method ofproduction given by way of example in the accompanying drawings inwhich:

FIG. 1 represents the rotor of the machining unit according to theinvention;

FIGS. 2A and 2AA represent frontal views of the rotating head of themachining unit, according to the invention, in the first position inwhich one of the cutters plunges into the material to be machined;

FIGS. 2B and 2BB represent frontal views of the rotating head of themachining unit, according to the invention, in a second position inwhich the cutters are withdrawn from the material to be machined;

FIGS. 2C and 2CC represent frontal views of the rotating head of themachining unit, according to the invention, in which the cutter oppositeto the one that plunges into the material to be machined in FIG. 2AA isin a working position;

FIG. 3 represents an enlarged view of the rotating head in which thecommand sleeve is in a primary position, corresponding to the positionsof the cutters according to FIGS. 2A, 2AA, 2B, 2BB, 2C and 2CC;

FIGS. 4A, 4AA, 4B, 4BB, 4C, 4CC represent similar views to those ofFIGS. 2A, 2AA, 2B, 2BB, 2C, 2CC, respectively, but for a second positionof the command sleeve;

FIG. 5 represents an enlarged view of the rotating head in which thecommand sleeve is in the second position corresponding to the positionsof the cutters according to FIGS. 4A, 4AA, 4B, 4BB, 4C and 4CC; and

FIG. 6 represents an elevated view showing more specifically the plungecommand of the tools.

DETAILED DESCRIPTION OF THE INVENTION

With respect to the drawings, the machining unit represented is composedof three essential elements that are the rotor, the phase displacementcommand device and the drive device of the tools.

The rotor 100, shown in FIG. 1, comprises of a rotating shaft 1supported by a front bearing 2 and a rear bearing 3 which is composed oftwo bearings 3a and 3b mounted, at oblique points, in a sliding fit case3c. The front and rear bearings are mounted in tandem and preloaded bymeans of a compression spring 4. The rotation of the spindle 101 isachieved by means of a notched pulley 5 coupled to a drive motor (notshown) by a notched belt 6.

The material to be machined, in the form of a wire, is guided by aguiding cylinder 7 located in an axial conduit of the rotor andsupported by two preloaded bearings 8. A system of grips (not shown)assures feed of the material.

Shaft 1 contains four borings, extending parallel to but offset from theaxis of rotation, in which the cutter carrier axles 9a, 9b, 9c and 9dare mounted. The cutter carrier axles 9a and 9c are identical as well asthe cutter carrier axles 9b and 9d. These axles are supported in frontby a double needle bearing 10 and in the back by a simple needle bearing11 housed in a cap 12. Between these bearings are located,interconnected with the cutter carrier axles, command levers 13a, 13b,13c and 13d (see FIG. 2). One will note that levers 13a and 13c areidentical as well as 13b and 13d. Levers 13a and 13c support helicalportions 14a and 14c and levers 13b and 13d support helical portions 14band 14d. The helical portions 14a and 14c are identical as well ashelical portions 14b and 14d, but these last two are inverted withrespect to the preceding ones. Push springs 15 (see FIG. 2) assureengagement of the work piece while screws 16 allow adjustment of theangular clearance of the command levers and consequently of thecorresponding cutter carrier axles.

Cutter carriers 17 are mounted at the front end of the cutter carrieraxles 9a, 9b, 9c and 9d. The positioning of the cutters, to a desireddiameter from a cutting line 18 of the cutters, is obtained by pivotingthe cutter carrier axles 9a to 9d.

This pivoting is accomplished by axial displacement of a command sleeve19 which carries, at its front end, two ellipsoidal surfaces 20a and 20bdesigned to be in contact with the helical portions 14a and 14b. Whenthe command sleeve is in the middle position, that is to say anintermediate position with respect to those pictured in FIGS. 3 and 5,the springs 15 bias levers 13a to 13d to pivot, and consequently thecorresponding cutter carrier axles 9a to 9d, in such a way that theypress against the thrust bearing screw 16. These screws are adjusted sothat, in this position of the command sleeve 19, the helical directingsurfaces are detached from the ellipsoidal surfaces 20a and 20b.

When surface 20a comes into contact with the helical portion 14a,following movement of the command sleeve 19 to the right, as shown inFIG. 3, it causes the pivoting of the command lever 13a and of thecutter carrier axle 9a and consequently a plunging of the cutter intothe material to be machined. The cutter carrier lever 13b remainsagainst the screw 16. It is the same for cutter carrier levers 13c and13d.

When surface 20b comes into contact with the helical portion 14b,following movement of the command sleeve 19 to the left, as shown inFIG. 5, it engages the pivoting of lever 13b and of the cutter carrieraxle 9b and consequently plunges of the cutter into the material. Thecutter carrier lever 13a remains against the screw 16. It is the samefor cutter carrier levers 13c and 13d.

In order to work with axles 9c and 9d, one must only rotate the commandsleeve 19 a quarter turn with respect to shaft 1. The above discussionalso describes the operation of cutter carrier axles 9c and 9d,respectively, instead of cutter carrier axles 9a and 9d.

This rotation of the command sleeve 19 is commenced by a phasedisplacement device. This device includes a pulley 22 linked to thesleeve 19 via two cotter pins 21 which ensure the rotational couplingbut which allow the command sleeve 19 to move freely axially relative topulley 22. This pulley is equipped with two circular grooves 22A theinteriors of which are located thrust bearings 23 interconnected withthe shaft 1. The angle of entry is such that it allows pivoting ofpulley 22 of a quarter turn relative to shaft 1. The entries also serveto maintain the axial position of pulley 22 by means of thrust bearings23.

The pulley 5 is coupled to a reverse pulley 25 by way of a belt 24. Thisreverse pulley is rotatably mounted on a tubular support 27 by means ofa bearing 26. On this same support, a second rotatable pulley 28 ismounted by means of a bearing 29. This rotatable pulley 28 is coupled topulley 22 to drive it by means of a notched belt 30. The reverse pulley25 is linked to a shaft 31 by two contacts 32, respectively, engaged intwo helical grooves 33. The reverse pulley 28 is linked to shaft 31 bytwo contacts 34 engaged in two longitudinal grooves 35. The shaft 31 canbe moved axially by means of a piston 36. This last piece has at its endwith respect to shaft 31 a bell cover 37 into which a pressure bearing38 is mounted. An interior ring of this bearing is fixed to shaft 31.Position sensors 39 limit the path of the piston 36 and provide areceipt signal of its movement.

When the shaft 31 is in the axial-position, shown in FIG. 1, the pulley22, and consequently the command sleeve 19, turns exactly at the samespeed as shaft I because the notched pulleys 5 and 22, respectivelypulleys 25 and 28, have the same number of teeth. The angular positionof the shaft 1 with respect to that of pulley 22 remains constant.

When the piston 36 is ordered to move to the left (FIG. 1), it pushesthe shaft 31 by means of the bell cover 37 and the pressure bearing 38.In this manner, the helical grooves 33 create a relative angulardisplacement between pulleys 25 and 28 which is transmitted by belts 24and 30 and causes relative movement of pulley 22 with respect toshaft 1. The specific choice of the pitch of the helical grooves 33; ofthe path of piston 36, and the relationship between pulleys 5 and 25, 22and 28, respectively, allows an angle of rotation of 90° to be obtainedbetween the pulley 22 integral with the sleeve 19 and the pulley 5integral with the shaft 1. This angle can be adjusted by means of anadjusting screw 40 that limits the path of the piston 36.

The choice of one set of tools, or another, can only be made when thecommand sleeve 19 is in intermediary position, that is to say there isno contact between the inclined portions 14a to 14d and the commandsurfaces 20a and 20d of ellipsoidal forms.

The number of tools is not limited to two pairs and if space allows oneor several pairs of supplementary tools can be mounted on the spindle.The phase displacement command device described above is a means toselect a set of tools with which a machine operator wishes to work. Thismechanism could be replaced by another device, for example, a gearsystem whose function would therefore be equivalent to that of the drivepulleys.

The drive device of the tools is described in more detail with thereferences to FIGS. 1 and 6. Its function is to move the command sleeve19, during the rotation of the spindle, in order to guarantee the plungeof the cutters. To achieve this, a support 51 is mounted above theframework 52 of the spindle, this support having an axle 50 about whicha command lever 49 can pivot. This lever includes, near the spindle, twodrive nuts 53 centered by axles 54, which are engaged respectively intwo grooves located on the opposite sides of a sleeve 42 (see FIG. 1)mounted on the command sleeve 19. While pivoting, the lever 49 axiallymoves the command sleeve 19, via axles 54, the nuts 53, the sleeve 42and a pair of ball bearings 41 in an inclined preloaded contact.

The member that generates this movement, is a servomotor 43 with anintegrated position sensor, designed to rotate a ball screw 45 by meansof a coupling 44. A bearing 56 is designed to take up axial stress whilethe other end of the ball screw 45 is supported by a bearing 57 housedin a block 55 and fixed on the support 51. The nut 46 of the ball screw45 is mounted in a block 47 that can pivot relative to an axis 48supported by the lever 49.

When the motor 43 causes a given rotational movement, this istransformed into a linear movement of the nut 46 and of the block 47 bythe threaded system. This block that is linked to the lever 49 by theaxis 48, pivots the lever 49, and as a result that the distances betweenaxes 50 and 48 and 50 and 54, respectively, are equal, the commandsleeve 19 moves a distance exactly equal to the movement of block 47. Acareful assembly can avoid play in the transmission. moves a distanceexactly equal to the movement of block 47. A careful assembly can avoidplay in the transmission.

I claim:
 1. A machining unit with a rotating head with at least twopairs of pivoting tools for machining of a non-rotating piece centeredalong an axis of rotation, comprising:a framework upon which a rotor ismounted including the rotating head and a spindle integral with thishead, the rotor being provided with an axial conduit for a guidingcylinder of a wire to be machined, and coupled with means for providingrotational drive; means for axial guidance of the piece, this meansbeing mounted by bearings in the spindle or the rotating head; means formaintaining and axially moving the piece; at least four tool supportsmounted on the rotating head in such a way as to pivot around respectiveaxles extending parallel to the rotation axis, each support comprising atransversely arranged command lever, and means for controlling pivoting,in conjunction with said command lever and including a rotating commandelement, that is axially movable in the rotor, and coupled to means foraxially moving a command sleeve, and pairs of support membersrespectively arranged on each command lever and on the correspondingrotating element, each pair of drive mechanisms including a directingsurface and a drive surface supporting itself against the directingsurface, in a variable position, in relation to the movement of therotating command element, said directing surface being located on thetool support and the corresponding drive surface being located on therotating command element, each directing surface corresponding to apivoting tool support having the shape of an helical portion whose axiscoincides with the pivoting axis of said support, and the helicaldirecting surfaces having respective pitches of opposite direction,wherein the command sleeve (19) is mounted coaxially on said spindle(101), in order to slide axially and to occupy a primary position, asecondary position and a middle position, this sleeve having twoellipsoidal drive surfaces (20a and 20b) at one of its ends, designed toco-operate with the helical directing surfaces (14a, 14b, 14c and 14d)of the drive members and to execute the plunge of the tools, and a phasedisplacement device designed to cause said command sleeve (19) to rotatea predetermined angle around its axis.
 2. The unit according to claim 1,wherein the means for axially moving the command sleeve (19) includes acommand lever (49) pivoting about an axle (50) mounted on a support (51)fixed to the framework (52) carrying the spindle (101), this levercomprising two drive nuts (53) centered about axles (54) and engagingrespectively two grooves located on opposite sides of a sleeve (42)mounted coaxially on the command sleeve (19).
 3. The unit according toclaim 2, wherein the sleeve (42) is mounted on the command sleeve (19)by two ball bearings (41) with oblique preloaded contacts.
 4. The unitaccording to claim 1, wherein the phase displacement device includes apulley (22) linked to the command sleeve (19) by two cotter pins (21)that assure a rotational coupling between said pulley and said sleeveand that allow the latter free to move axially, said pulley beingcoupled to a rotatable pulley (28) mounted on a tubular support (27)supporting a reverse pulley (25) mounted freely and linked to a drivepulley (5) mounted on the spindle and driven by a drive motor.
 5. Theunit according to claim 4, wherein the coupling between the pulley (22)and the rotatable pulley (28) is executed by means of a belt (30). 6.The unit according to claim 1, wherein the coupling between the reversepulley (25) and the drive pulley (5) is executed by means of a belt(24).
 7. The unit according to claim 4, wherein the phase displacementdevice includes means to change the angular position of the rotatablepulley (28) relative to the reverse pulley (25).
 8. The unit accordingto claim 7 wherein the means to change the angular position of the twopulleys includes two interdependent contacts (32) integral with thereverse pulley (25), engaged in two helical grooves (33) of a shaft (31)and two interdependent contacts integral with the rotatable pulley (28)engaged in two longitudinal grooves (35) of said shaft (31) as well as amember (36) designed to move said shaft (31) axially.
 9. The unitaccording to claim 8, wherein said member (36) is a piston and that saidpiston is linked to the shaft (31) by means of a bell cover (37) and athrust bearing (38) mounted at one end of this shaft.
 10. The unitaccording to claim 9, wherein said piston (36) is linked to positionsensors designed to provide a receipt signal of its movement.
 11. Theunit according to claim 8, wherein the rotatable pulley (28) and thereverse pulley (25) are notched pulleys that have the same number ofteeth.
 12. The unit according to claim 8, wherein the helical grooves(33) are located in such a way that when the, piston (36) moves theshaft (31) from a first position towards a second position, the angulardisplacement of the pulley (22) integral with the command sleeve (19)with respect to the shaft (1) integral with the spindle (101), is 90°when the number of pairs of tools carried by the machining head is equalto two.
 13. The unit according to claim 12, wherein the piston (36) isjoined to an adjusting screw (40) which limits its path.